Recovering a Juniper J4350 should be easy because the manual says so. Just remember to take your screwdriver ;-)

A few weeks ago my lab router fell off the network. The console showed me repeating hash (#) symbols followed by a HEX dump of a few characters. I figured this looked bad...don’t know what happened. Since I didn’t need it right away I’ve left it until now. So time to have a go at fixing this now.

  • You’ll have to remove chassis from the rack (4 cage screws).
  • Put the router on the bench and take off the rack ears from both sides of the chassis.
  • Now go to the back of the chassis and you’ll see three black screws on the top. You need to unscrew these.
  • Along each of the sides of the chassis (again toward the top of the case) you’ll see three more screws. Unscrew these on both sides.
  • Now the case lid should come off.

Screen shot 2011-05-08 at 20.40.08

With the router lid off I now see there are 4 x PC3200 DIMMS toward the left hand side and the compact flash (256MB) is sat snugly against the motherboard. My task here is to reformat the flash with the ‘install’ image from the Juniper software download page. Now I’ve chosen 9.3 because I felt like it but notice that there are three flavours available for 256, 512 and 1024MB flash cards...choose the right one for your flash size - this one shows the 512MB version.

Screen shot 2011-05-08 at 20.45.16

I’ve gotten the image and extracted the flash from the 4350 (man that was a pain too because the fan buffer was in the way). Now, I don’t have a flash/PCMCIA slot in my iMAC but I do have a printer connected to it with a compact flash reader so I figure I’m going to give it a try with that. Flash plugged in I see this error by loading the Terminal, changing to root (sudo -i) then doing a ‘dmesg’ to see any kernel messages.

Screen shot 2011-05-08 at 20.36.25

Check it out, maybe my luck is changing. I see /dev/disk2s1 must be my Juniper flash card. Great now I can format it. First things first I need to uncompress the gzip file I just downloaded from Juniper. The original file was junos-jsr-9.3R4.4-export-cf256.gz. I run ‘gzip -d junos-jsr-9.3R4.4-export-cf256.gz’ to extract the file. Now I run the old faithful ‘dd’ (disk duplicate) command which is fairly common on *nix platforms to copy the contents of the archive onto the flash.

Screen shot 2011-05-08 at 20.36.01

....I wait...and wait some more...then

Screen shot 2011-05-08 at 20.52.07

Awesome - looks like the data is on now. So I replace the CF card into the chassis and power on (there is no way I’m putting all those screws back in just yet) didn’t work ;-( All I see is #’s and the fan keeps spinning up and down.

So I tried a USB stick. I took out the CF card because that is booted first. Then plug the USB flash into the front of the router and power on.

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